def print_models(unprinted_designs, completed_models):
     while unprinted_designs:
         current_design = unprinted_designs.pop()
         print("Printing model: " + current_design)
         completed_models.append(current_design)
def show_completed_models(completed_models):
      print("\nThe following models have been printed:")
      for completed_model in completed_models:
        print(completed_model)
unprinted_designs = ['iphone case', 'robot pendant', 'dodecahedron']
completed_models = []
print_models(unprinted_designs, completed_models)
show_completed_models(completed_models)